Lähipisteessä

Lähipisteessä is a Finnish term that translates to "at the near point" or "at close range." It generally refers to the closest distance at which an object can be clearly seen or focused upon by the eye. This concept is fundamental in optics and vision science.

The lähipisteessä for a healthy young adult is typically around 25 centimeters (approximately 10 inches). This is the distance at which the ciliary muscles in the eye are maximally contracted, allowing the lens to become as convex as possible to focus light from nearby objects onto the retina. As individuals age, the flexibility of the eye's lens decreases, a condition known as presbyopia, which causes the lähipisteessä to recede further away. This means that older individuals may need reading glasses to see objects clearly at their usual reading distance.

Understanding the lähipisteessä is important for various applications. In ophthalmology, it is a standard measurement used to assess visual function and detect age-related changes in the eye. In optics, it influences the design of lenses for glasses and other optical instruments, ensuring they can effectively correct vision for near tasks. The concept also applies to photography and microscopy, where it defines the closest focusing distance of a lens or system.